With a laser experiment, scientists have succeeded in generating more energy in a nuclear fusion than the fuel previously absorbed. An important milestone on the way to a working fusion reactor.
Livemore (USA) It is one of the greatest goals of the 21st century that scientists, physicists, technicians and engineers around the world are chasing after: to build a burning fusion reactor that, modeled on the stars, will provide electricity for millions of people. An experiment has now reached an important milestone. Scientists heated a sample of deuterium and tritium with laser beams so suddenly that nuclear fusion occurred inside the sample container. For the first time, more energy was released through fusion than the fuel had previously absorbed.
Temperatures of several million degrees Celsius and enormous pressure prevail inside stars. These two properties ensure that atomic nuclei fuse with each other. Nuclear fusion releases more energy than nuclear fission, and it is precisely this energy that makes the stars burn. Nuclear fusion can not only make stars shine, but theoretically also light bulbs on earth. In the future, fusion reactors, also known as fusion power plants, could solve all the energy problems on earth without producing greenhouse gases or radioactive waste and without touching the fossil fuels in the ground. In addition, nuclear fusion is a very safe form of energy production because it does not generate a chain reaction and can be switched off immediately in the event of a malfunction.
However, the road to a functioning fusion reactor is still very rocky. For decades, scientists have encountered new, unforeseeable difficulties and have had to work hard for every little step forward.
Omar Hurricane of the National Ignition Facility at the Lawrence Livermore National Laboratory in California proudly reports: “Our experiment shows an order of magnitude improvement in energy production compared to previous attempts.”
The scientists have 192 of the world’s most powerful lasers at their disposal for the experiment, the technology of which alone fills several large halls. The lasers are arranged to focus with a tiny cylinder. This is just a centimeter long and about 3 millimeters in diameter. The total output of the lasers is one terawatt, i.e. one trillion watts.
The laser impulses of the high-performance laser systems are synchronized in such a way that within a few millionths of a second they direct the entire energy onto the small sphere inside the cylinder. The fuel heats up enormously and turns into a plasma. During this process, the temperatures and pressures inside the cylinder are so high that the heavy hydrogen begins to fuse.
In four of several dozen experiments, the energy generated by nuclear fusion was greater than the amount of energy absorbed by the laser bombardment. However, it is not enough to generate energy, because only one hundredth of the energy of the lasers gets into the interior of the cylinder during the experiment. The remaining energy is lost in the vaporization of the cylinder and other processes.
Although the experiments in Livemore, California, provide important insights for fusion research, the aim of the experiments is not to generate energy, but to further develop thermonuclear weapons. The American military can thus increase the safety, service life and destructive power of atomic bombs without violating international treaties banning nuclear weapons tests.
